grids

[mapsam]

Adds the grids section for 3.0

cc @GretaCB

[mapsam]

If the array doesn't contain any entries, interactivity is not supported for this tileset.

@GretaCB I updated (bold) this to

If the array doesn't contain any entries, UTF-Grid interactivity is not supported for this tileset.

The original sentence felt a little "pre GL" in that interactivity wasn't possible unless you used UTF-Grid tiles. Do you think we could add an additional note to this saying something like:

Note: UTF-Grid interactivity predates GL-based map rendering and interaction. Map interactivity is now generally defined outside of the TileJSON specification and is dependent on the rendering library's features.

Similarly, it'd be worth opening a ticket suggesting we remove grids from v4.

[mapsam]

I've added a checkbox in #36 to review the usage of "interactivity" in relation to UTF-grid and GL-based maps.

[GretaCB]

Do you think we could add an additional note to this saying something like:

@mapsam Totally. I added over at #52